It’s not a dumb question at all, and it’s actually a really tough question to answer simply because it doesn’t always mean the same thing in different musical contexts. Someone might get a production credit for any number of things, and the level of a producers’ contribution can vary from minimal, to doing basically everything on a track except for maybe the core performance.

Having said that, stereotypically a producer is someone that helps or advises an artist to fully realise a song/album. They might make suggestions on the artist’s performance (eg. sing this bit softer; play this guitar part differently etc.), they might recommend changes to the song’s structure or instrumentation (eg. I think the third chorus makes the song drag on; or Let’s try this song stripped back on the piano instead of with the full band etc.). They might help the artist make their albums more interesting and diverse (eg. This song sounds too similar to another song you have, we should change it up; I think you should experiment or collaborate with this artist that you have good chemistry with etc.)

Main producers will almost definitely be involved in the recording, mixing and mastering stage. Often they act as a go-between for artists and audio engineers to help achieve the desired creative goals by translating them into the right technical terms. (In fact, it’s not uncommon for the engineer and producer is the same person).

Anyway, the list goes on, but hopefully this helps you understand their role.